Study On Producing Biodiesel With Circulating Gaseous Esterification And Transesterification And Water Vapour Distillation

Biodiesel catches many countries' eye on its renewability, environmental protection and substitutability of petrochemical diesel, and becomes the most popular petrochemical diesel substitute. Among current synthesis methods, transesterification is the main industrial production method of biodiesel now. The current transesterification technique improves the conversion rate by two-transesterification and the purity of biodiesel by consumption of a great deal of water. Moreover, the material is anhydrous and acid value is less than 1.0(AV<1.0). This kind of technique is complicated in operation and energy consumption is higher. It easily causes secondary pollution of environment and byproduct losing, so the production cost is higher. Aiming at these problems, the thesis designs the technique and experiment equipment of 'circulating gaseous esterification and transesterification and water vapour distillation' that produces biodiesel and reclaims byproduct under the foundation of summing up domestic and abroad literatures. The optimal process parameter of seven deffirent materials (waste fat from restaurant, Jatropha Curcas oil, rape oil, soybean oil, linseed oil, peanut oil, palm oil) of producing biodiesel is studied with this technique and experiment equipment. The acquired parameters are the follows:(1)Circulating gaseous esterification processTemperature: the esterification reactor is95~105℃, the methanol vapour reactor is 60~70℃; Reflux ratio of methanol rectification: 2.0-2.5; Discharge of methanol vapour: 6L/min per 100 grams oil; Acid-catalyst: 0.2 %~1.0% of oil weight; Reaction time: 30-120 mins.(2)Transesterification processTemperature: 60~80℃; Number of times:once; Reaction time: 60-120 mins; Methanol: 20-25% of oil weight; Alkali-catalyst: 0.4-1.5% of oil weight.(3)Biodiesel refining processTemperature: liquid phase is 180-280℃, gas phase is 120-20℃, water vapour is 95~105℃; Discharge of water vapour: 5L/min per 100 grams oil.This technique haven four innovation points:(1)Methanol firstly is gasified and then enters the esterification reactor. Thus the efficiency of esterification is increased greatly. (2)It adds the circulation of methanol vapour, reclaims effectively residual methanol vapour in the esterification, and enhances the utilization of methanol. The methanol is almost not wasted in the esterification. (3)The acid value of material in transesterification is broadened to 5.0 under the condition of this technique. (4)The combination of reclamation of byproducts(glycerin and potassium sulfate) and esterification has realized the biodiesel refining and byproduct recycling. This technique increases efficiency and decreases production cost.Based on technique research, the thesis further studies the peculiarity of seven different biodiesel, such is caloricity, viscosity, vaporability and ignition point. Operation test of diesel engine indicates that liodiesel may directly be used without changing diesel engine.After full inquiring and comprehensive analysis of oil-crops, the thesis figures out our country has not et the condition of massive developing biodiesel because our oil resorce mainly is edible oil and inputs is 00 million tons per year. It has not economic feasibility in production biodiesel. For this reason, the thesis oints out that development of our biodiesel industry may go through three stages, and brings out six itional suggestions.